In vivo evaluation of hyaluronic acid based in situ hydrogel for prolonged release of Avastin by intravitreal injection

Conference Theme: Leading Eye and Vision ResearchSession 477: Drug delivery #2Purpose: To evaluate the biocompatibility and 6 months in vivo release of Avastin from a hyaluronic acid based in situ hydrogel after intravitreal injection in rabbit eye. Methods: The in situ hydrogel is formed by the chemical crosslinking of two polymer solutions, the vinylsulfonate hyaluronic acid (HA-VS) and thiolated dextran (Dex-SH) using catalyst-free click chemistry in aqueous phase (Yu and Chau 2012). The pH 7.4 buffered HA-VS, Dex-SH and Avastin were mixed on ice and injected to the vitreous of rabbits with 30 G needle. The biocompatibility was evaluated by binocular indirect ophthalmoscope (BIO), full-field ERG and histology at various time points from 1 week to 3 months. The concentrations of both total and active Avastin in rabbit vitreous were determined by ELISA assay. Results: A transparent gel is seen in the vitreous after injection. The low viscosity of the mixture made injection easy even through 30G needle, and the fast gelation at body temperature (